Abaixo está uma instrução que descreve uma tarefa de geração de SQL, combinada com uma entrada que fornece mais contexto sobre os esquemas de tabela disponíveis. Escreva o código SQL que responda adequadamente à solicitação
 ###Instrução: Qual é o significado de "Since", quando a Taxa de Transferência é "£ 12m"?
 ###Tabelas: CREATE TABLE squad_information (squad_information_id AUTO_INCREMENT PRIMARY KEY, Nat. VARCHAR, Name VARCHAR, Since VARCHAR, Goals INT, Ends VARCHAR, Transfer fee VARCHAR) CREATE TABLE winners_knockout (winners_knockout_id AUTO_INCREMENT PRIMARY KEY, Home (1st leg) VARCHAR, Home (2nd leg) VARCHAR, 1st Leg VARCHAR, 2nd leg VARCHAR, Aggregate VARCHAR) CREATE TABLE 2007_data (2007_data_id AUTO_INCREMENT PRIMARY KEY, Rank INT, Airport VARCHAR, Total Passengers INT, % Change 2006/2007 VARCHAR, International Passengers INT, Domestic Passengers INT, Transit Passengers INT, Aircraft Movements INT, Freight (Metric Tonnes) INT) CREATE TABLE -_11_seats (-_11_seats_id AUTO_INCREMENT PRIMARY KEY, Riding VARCHAR, Candidate's Name VARCHAR, Gender VARCHAR, Residence VARCHAR, Occupation VARCHAR, Votes INT, Rank VARCHAR) CREATE TABLE lpga_tour_career_summary (lpga_tour_career_summary_id AUTO_INCREMENT PRIMARY KEY, Year INT, Tournaments played INT, Cuts made INT, Wins INT, 2nd INT, 3rd INT, Top 10s INT, Best finish VARCHAR, Earnings ( $ ) INT, Money list rank VARCHAR, Scoring average VARCHAR, Scoring rank VARCHAR)  
SELECT Since FROM squad_information WHERE Transfer fee = £ 12m